Graphics tablets or digitizer tablets are computer peripherals used for drawing or navigating on a computer system. Graphics tablets typically include a flat sensing area and an associated tool that is usually either pen shaped or mouse shaped. These tablets measure X and Y coordinate positions as well as other parameters, such as pen tip pressure, pen tilt, mouse buttons, mouse rotation, etc. Various technologies can be used to implement the graphics tablet. One exemplary technology is resistive, where voltage ratios are measured across conductive sheets to determine position. Another exemplary technology is electromagnetic, where position is detected by interpolating signal strength across a series of inductive coils. Various other technologies are available including triangulating sound or light waves, measuring applied force at corners of the tablet, measuring electric field distortions, etc. The resolution of the detected position with these technologies is typically in the range of 0.025 mm or better.
The positional information from the tablet is most often used to move a pointer on the display during navigation, or to draw a “virtual ink” on the display during drawing operations. Since the resolution of a display is much less than the tablet, (roughly 0.25 mm per pixel) a coordinate transformation is needed to establish a relationship between the tablet and the display. The default transformation typically scales the tablet coordinates such that the entire width of the tablet scales to the entire width of the computer system desktop (where the desktop is a tiled collection of one or more monitors). The entire tablet height is typically scaled to the entire height of the desktop.
Systems with multiple monitors used to create a large desktop are growing in popularity. With small opaque digitizer tablets, mapping the small digitizer tablet across two or more monitors, or even one large monitor, results in a large physical scale difference so that a very small hand movement results in a large movement on the screen. For example, with a 4 by 5 inch tablet mapped to dual 19 inch monitors, a one inch movement on the tablet results in approximately 6 inches of movement on the monitors. In this arrangement, it is difficult for a user to perform a precise amount of movement on the desktop.